Galactoseismology: How Earthquakes in Space Can Help Us Find Black Holes

Monday, 11 January 2016 - 12:52PM
Astrophysics
Physics
Monday, 11 January 2016 - 12:52PM
Galactoseismology: How Earthquakes in Space Can Help Us Find Black Holes
Scientists have come up with some pretty far-out methods in the ongoing hunt for dark matter. A new field, pioneered by RIT astronomer Dr. Sukanya Chakrabarti, is known as galactoseismology, and focuses on the earthquake-like ripples in our galaxy. 

These ripples are caused by seismic waves in the galaxy, and astronomers first observed them over a decade ago. Scientists now believe that the waves were caused by an unseen galaxy made of dark matter that came into contact with our galaxy hundreds of millions of years ago.

Opening quote
"It's a bit like throwing a stone into a pond and making ripples," said Chakrabarti at a press conference at the 227th meeting of the American Astronomical Society (via Astronomy Now). "Of course we aren't talking about a pond, but our galaxy, which is tens of thousands of light-years across, and made of stars and gas, but the result is the same - ripples!"
Closing quote


By studying these waves, galactoseismologists can infer the dark matter content, location, and properties of nearby hidden galaxies. Just as seismologists back on Earth analyze waves to infer properties about about planet's interior, Chakrabarti uses waves in the galactic disk to map the interior structure and mass of galaxies.

Opening quote
"You can infer the dark matter content of dwarf galaxies, where they ate, as well as properties of the interior of galaxies by looking at observable disturbances in the gas disk," she explained.
Closing quote


Chakrabarti's team first successfully used spectroscopic observations to calculate the speed of three stars in the Norma constellation. These stars are known as Cepheid variables, and are used as yardsticks to measure the distance in galaxies. They then went on to mark the location of a dwarf galaxy approximately 300,000 light years away, which comprises mostly dark matter. To give some perspective to this incredible feat, the Milky Way ends about 48,000 light years away from Earth. 
Chakrabarti's current study tracks a cluster of Cepheid variables which are traveling at an average speed of 450,000 miles per hour, 437,000 MPH faster than the stars in the stellar disk of the Milky Way.

Opening quote
"The radical velocity of the Cepheid variables is the last piece of evidence that we've been looking for," says Chakrabarti, "You can immediately conclude that they are not part of our galaxy." She continues, "The original prediction was based on observed waves in the outer gas disk of our galaxy which lead to a specific prediction for how massive this dark matter dominated dwarf galaxy would have to be to produce these waves... We're trying to infer things about the interior of galaxies and how much dark matter there is and how much there has to be to produce these disturbances."
Closing quote
Science
Science News
Astrophysics
Physics

Load Comments